Reducing Water Bills

How much water am I using in the house?

Some tips from Alan Benn

It's always a great time to think about how you use water in the house.

How much water should a person need for personal use?

When I review people's water bills and show them on their bill how many litres they are using per day, they usually look at me and ask - "is that a lot?" I like to think about what is a "reasonable" amount of water to use each day.

In Perth over a whole year, the average per person for water use for inside the house is 150L per person per day (ie excluding garden watering, pool refilling, etc). When I visit a house with 2-3 people living there, it's common to see 300 - 500L/day on the winter bills. That's the first exercise for you readers - dig out a water bill covering last year's winter period - any 2 months between May and August.

Take a closer look: Look for the chart and read your average daily water consumption - does it fit to 100-200L/person/day?

150L is 15 buckets full - that sounds like quite a lot, eh? So where does that water get used?

Where does the water get used?

Number 1 is the shower. If you have a waterwise shower head, it will be using 9L/minute. If you are good and only have 4min showers, then you will use 4 x 9L = 36L in the shower. That's about a quarter of the 150L daily amount already. If you have an old high flow shower head (25L/min) and stay in the shower for 10mins you could be using 250L - quite a difference, eh?

Number 2 is toilet flushing. Most people now have standard dual flush toilets which use 4L per half flush and 9L per full flush. If you flush say 5 times per day, 2 full and 3 half, that's another 30L. Some people still have old single flush cisterns at 12L/ flush. Some have even better dual flushers at 3/6L.

Number 3 could be the washing machine. If you have a front loader, it probably uses 60-70L per load. If you can do all your personal weekly washing in 2 loads, that's about 140L/week, 20L/day. If you can get it all done in 1 load, that's 10L/day. If you have a big top loader it could be using twice as much water - 150L/load, although some have level adjustments or load sensors.

Number 4 is maybe washing up. Do you fill the sink with 10L/load? Twice per day = 20L? But that washing up is shared among all house members, so let's say 10L each?

Other: Cooking is probably just a few litres to boil vegies, pasta etc.
Hand washing and drinks a few litres each.

So we come to a total of say 36 + 30 + 20 +10 + 5 = about 100L per person per day. So why is the Perth average 150L? What do your bills show? Use some of the information above to recalculate for your situation and see how it compares to what your bill (from last year) says.
You can monitor your water use by reading your water meter

If you don't want to wait until your next bill comes, try using your water meter to check how much water you use over a few days. You can read the water meter down to each litre you use, so you can see how you're going and maybe find problems before the next bill arrives.

Leaking toilet cisterns

The most common factor I find when water use is unusually high is a leaking toilet cistern. Even if you can't hear the cistern hissing or see water trickling in to the bowl there can often be a small leak of 20-40L/day.

How to check: Put a sheet of toilet paper at the back of the bowl (when it hasn't been flushed for an hour or so). If the paper sticks to the bowl and then a wet patch grows from the top down, it shows there's a small leak. Time to get that fixed!

Alan Benn

Sustainability Auditor

Based on a post first written for Environment House by Alan Benn on 05/04/2016